A department wishing to operate a compressor without running the fire pump will need some form of auxiliary cooling. A compressor that is allowed to run without adequate cooling will quickly overheat and damage the compressor. The overheating situation may be due to the pump operator failing to circulate water through the compressor cooler or the result of debris plugging the oil cooler strainer. This cooling is usually provided through the use of an air-to-oil cooler. The air-to-oil cooler acts as a radiator for the compressor oil, allowing the oil to be cooled independently of the water pump circulation. Most caf installations provided with air-to-oil coolers will continue to use the standard fire pump water cooler as well. Operating both systems adds a level of protection for the compressor.

Departments that may be concerned about running their compressor without the cooling of the fire pump may specify an interlock device that prevents compressor engagement without the fire pump being engaged as well. Any additional cooling provided to the compressor also will act as a safeguard for the compressor should the water flow to the standard cooler be restricted at any time.

Another air system issue that must not be overlooked is that the compressor often has to provide air for auxiliary uses. When specifying a caf system, departments that may need high volumes of air should consider high-flow air pressure regulators, air dryers and delivery devices all designed to flow the capacity of the compressor. These items are much easier to design into the system in the beginning rather than trying to add them at a later date.

Maintenance

There are some simple things to consider that may improve your department’s abilities to maintain your CAF system:

Discharge outlet locations. Many departments have all their hose connections buried in or under hose beds. Connections located where they may be accessed easily without disturbing the hose loads will allow the operator to disconnect the hose loads and flow air from the discharges. The ability to flow air on a regular basis from a CAF system is important for the maintenance of the system. This air flow exercises all the key components in the systems and allows the operator to run and understand the system. A configuration that requires the unloading of a hose bed to flow air may result in an incomplete system check.

Strainer locations. Most CAF systems have several simple strainers built into them that need to be checked on a regular basis as part of a preventive maintenance program. These strainers include a foam concentrate strainer and a strainer in the water line feeding the compressor oil cooler. The frequency of the checks on these strainers will depend on several factors, including hours of use, quality of foam, or clarity or amount of debris in the water an apparatus pumps. Departments that depend on drafting from lakes or ponds may have to check and clean their strainers more frequently than a department that works only from a hydrant system. The location and access to these strainers are important. Strainers that are difficult to access or check will result in a reduced number of inspections and may lead to a system that does not perform as expected.

Other components. Departments should work with apparatus manufactures so that all items that need frequent or even periodic checks or maintenance are easily accessible. These items should include strainers, fluid level sight glasses, valves and filters. A CAF system that is maintained well will operate much more reliably and accurately.

Check valves. A typical CAF system uses check valves to keep the water, foam and air moving in the correct direction without one product backing into another system and contaminating it. Departments that have hard water or water that contains many minerals may find their check valves sticking. In many cases these check valves will stick in the closed position and not allow product out. Preconstruction discussions with the apparatus builder may eliminate these issues by confirming that the placement of the check valves allows water to naturally drain away from the valve.

This article is not designed to be a how-to or a must-have for a CAF system. It is intended to help generate discussion within fire department and between fire departments and fire apparatus manufactures as to what options are available and how departments can improve their systems’ abilities and capabilities.

Chris Hecht is chief of the Sister Bay/Liberty Grove Fire Department in Door County, Wis.